The diagnostic performance of PET/CT scans for the detection of para-aortic metastatic lymph nodes in patients with cervical cancer: A meta-analysis

Lymph node assessment in cervical cancer: current approaches

Cervical cancer (CC) is the fourth most common neoplasia in women worldwide. Although early-stage CC is often curable, 40 to 50% of patients are diagnosed at a locally advanced stage. Metastatic disease accounts for the principal cause of death. Lymph node (LN) status is a major factor impacting treatment options and prognosis. Historically, CC was staged based only on clinical findings. However, in 2018, imaging modalities and/or pathological findings were included in the International Federation of Gynecology and Obstetrics (FIGO) staging classification. In the last decades, LN status assessment has evolved considerably. Full pelvic lymphadenectomy used to be the only way to determine LN status. Currently, several options exist: surgery with full lymphadenectomy, sentinel lymph node (SLN) biopsy or imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). Regarding surgery, the SLN biopsy technique has become a standard procedure in cases of CC, with indocyanine green (ICG) being the preferred dye. Pelvic MRI is a valuable imaging technique modality for the evaluation of pelvic LNs. In locally advanced or in early-stage disease with suspicious LNs on CT scans or MRI, PET/CT is recommended for assessment of nodal and distant status. The best strategy for LN assessment remains a highly controversial topic in the literature. In this article, we aim to review and compare the advantages and limitations of each modality, i.e. imaging or surgical (lymphadenectomy or SLN biopsy) approaches.

Validation of the 2018 FIGO staging system for stage IIIC cervical cancer by determining the metabolic and radiomic heterogeneity of primary tumors based on 18F-FDG PET/CT

PURPOSE

This study aimed to validate the 2018 FIGO staging system of cervical cancer (CC) by determining the metabolic and radiomic heterogeneity of primary tumors between stage IIIC1 and IIIC2.

METHODS

168 patients with squamous cell CC underwent pre-treatment fluorine-18 fluorodeoxyglucose positron emission computed tomography (18F-FDG PET/CT) and were randomly allocated to training and testing cohorts with a 7:3 ratio. Radiomics features were extracted from the primary tumors based on CT and PET data. Ten metabolic parameters of the primary tumors were also assessed. After feature selection, three logistic regression radiomics models, involving (1) 2 CT features, (2) 3 PET features, and (3) 2 CT features + 3 PET features, respectively, and one random forest model were established. Finally, area under the curve (AUC) values and calibration curves were used to evaluate the 4 models.

RESULTS

The IIIC1 and IIIC2 groups did not differ significantly in age, weight, height, or the 10 major metabolic parameters (P > 0.05). The AUCs of the 4 models were 0.577, 0.639, 0.763, and 0.506, respectively, in the training cohort, and 0.789, 0.699, 0.761, and 0.538, respectively, in the testing cohort. The model fit of the logistic regression model based on CT + PET data was good in both the training and testing cohorts.

CONCLUSION

Our study offers additional diagnostic options for PALN metastasis, which could impact treatment decisions. Our results indirectly support the conclusions of previous studies recommending that primary tumors should be considered during IIIC staging.

The Role of Imaging in Cervical Cancer Staging: ESGO/ESTRO/ESP Guidelines (Update 2023)

Following the European Society of Gynaecological Oncology (ESGO), the European Society for Radiotherapy and Oncology (ESTRO), and the European Society of Pathology (ESP) joint guidelines (2018) for the management of patients with cervical cancer, treatment decisions should be guided by modern imaging techniques. After five years (2023), an update of the ESGO-ESTRO-ESP recommendations was performed, further confirming this statement. Transvaginal/transrectal ultrasound (TRS/TVS) or pelvic magnetic resonance (MRI) enables tumor delineation and precise assessment of its local extent, including the evaluation of the depth of infiltration in the bladder- or rectal wall. Additionally, both techniques have very high specificity to confirm the presence of metastatic pelvic lymph nodes but fail to exclude them due to insufficient sensitivity to detect small-volume metastases, as in any other currently available imaging modality. In early-stage disease (T1a to T2a1, except T1b3) with negative lymph nodes on TVS/TRS or MRI, surgicopathological staging should be performed. In all other situations, contrast-enhanced computed tomography (CECT) or 18F-fluorodeoxyglucose positron emission tomography combined with CT (PET-CT) is recommended to assess extrapelvic spread. This paper aims to review the evidence supporting the implementation of diagnostic imaging with a focus on ultrasound at primary diagnostic workup of cervical cancer.

Curative treatment for stage IIIC2 cervical cancer: what to expect?

Background

Since the GOG125 study, treating radically patients with positive para-aortic lymph nodes has been a valid approach. Nevertheless, literature lacks data on how to better treat these patients since they are usually excluded from trials. In this study, we aimed to report the outcomes of patients with advanced cervical cancer and positive para-aortic lymph nodes (PAN) treated in a single tertiary/academic institution and try to identify variables that may impact survival.

Materials and methods

We retrospectively reviewed patients with positive para-aortic lymph nodes treated in our institution. Demographic variables and treatment options were assessed and their impact on overall survival (OS), locorregional control, distant metastasis free survival, and para-aortic lymph node progression was analyzed.

Results

We assessed 65 patients treated from April 2010 to May 2017. Median OS was 38.7 months. Median locorregional and para-aortic progression free survivals were not reached. Median distant metastasis progression-free survival was 64.3 months. Better ECOG performance status (p > 0.001), concurrent chemotherapy (p = 0.031), and brachytherapy (p = 0.02) were independently related to better overall survival.

Conclusion

Patients with current stage IIIC2 cervix cancer may present long term survival. Treating positive PAN cervical cancer patients with concurrent chemoradiation including brachytherapy with curative intent should be standard. Poor PS and more advanced pelvic disease may represent a higher risk for worse outcomes. Distant metastases are still a challenge for disease control.

Prophylactic extended-field irradiation for locally advanced cervical cancer

Concomitant chemoradiotherapy is the standard treatment for locally advanced cervical cancer. Pelvic irradiation is commonly recommended for patients with negative para-aortic lymph nodes(PALNs). However, owing to the development of imaging-guided brachytherapy, distant failure has become the main failure pattern. The PALNs are a vital site of distant metastasis, and the para-aortic region may contain occult microscopic metastases that are barely detected owing to imaging technology restriction. The prognostic of patients who experienced PALN failure is dismal. Typically, there are four ways to decrease PALN failure. First, surgical staging can be performed to assess the occurrence of metastasis in the para-aortic region; however, the application of surgical staging is decreasing owing to controversial survival benefits and accompanying complications of surgery. Second, regular imaging surveillance and timely salvage of early recurrences could reduce PALN failure. Third, better systemic adjuvant therapy could be recommended since it has enormous potential to reduce distant metastases and improve overall survival. Fourth, performing prophylactic extended-field irradiation (EFI), including pelvic and para-aortic region irradiation, can sterilize occult microscopic metastases in the para-aortic region and improve survival. Prior investigations have revealed that prophylactic EFI could reduce PALN failure as well as distant metastasis and present the benefit of survival. Yet, owing to the serious morbidity induced by enlarged irradiation field in the era of conventional irradiation techniques, further research on EFI is stagnated. Nowadays, with the development of new technologies, intensity modulated radiation therapy can deliver a higher dose to tumors with acceptable toxicity. Prophylactic EFI regained attention. However, the inclusion criteria of prophylactic EFI in existing studies reveal great discrepancies. Thus, it is urgent to precisely identify indications for better survival and lower complications in patients with cervical cancer. In this review, we identify indications and summary guidelines for prophylactic EFI, which may provide a foundation for further trials and clinical applications.

Comparison of positron emission tomography with computed tomography examination with histopathological assessment of pelvic lymph nodes in patients with cervical cancer treated surgically

INTRODUCTION

According to the literature, fluor-18-fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG-PET-CT) is the most effective technique for the examination and detection of metastases in the lymph nodes in patients with cervical cancer. This study aimed to compare the diagnostic value of the preoperative evaluation using 18F-FDG-PET-CT with a histopathological examination of the lymph nodes removed during radical hysterectomy and pelvic lymph node dissection in patients with cervical cancer.

MATERIAL AND METHODS

Retrospective analysis covered the medical records of 42 patients with cervical cancer (stage IA-IB according to International Federation of Gynaecology and Obstetrics 2009) treated with radical Piver type III hysterectomy and pelvic lymph node dissection. The preoperative diagnosis was made using a PET/CT examination. Results: The result of the 18F-FDG-PET-CT examination highlighted a suspicion of lymph node metastases in 13 patients (31%). The histopathological examination confirmed this in 12 patients (29%). Metastatic lymph nodes were correctly diagnosed using 18F-FDG-PET-CT in 8 out of the 12 cases confirmed by the histopathological examination. In the patient-based study, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 66.8%, 83.3%, 61.5%, 86.2 % and 78.6%, respectively.

CONCLUSIONS

We confirmed the usefulness of PET in the preoperative assessment of cervical cancer advancement, especially in correlation with the new 2018 International Federation of Gynaecology and Obstetrics staging system.

Imaging to assist fertility-sparing surgery

Cytological screening and human papilloma virus testing has led to diagnosis of cervical cancer in young women at an earlier stage. Defining the full extent of the disease within the cervix with imaging aids the decision on feasibility of fertility-sparing surgical options, such as extended cone biopsy or trachelectomy. High spatial resolution images with maximal contrast between tumour and surrounding background are achieved with T2-weighted and diffusion-weighted (DW) magnetic resonance imaging (MRI) obtained using an endovaginal receiver coil. Tumour size and volume demonstrated in this way correlates between observers and with histology and differences between MRI and histology estimates of normal endocervical canal length are not significant. For planning fertility-sparing surgery, this imaging technique facilitates the best oncological outcome while minimising subsequent obstetric risks. Parametrial invasion may be assessed on large field of view T2-weighted MRI. The fat content of the parametrium limits the utility of DW imaging in this context, because fat typically shows diffusion restriction. The use of contrast-enhanced MRI for assessing the parametrium does not provide additional benefits to the T2-weighted images and the need for an extrinsic contrast agent merely adds additional complexity and cost. For nodal assessment, 18fluorodeoxyglucose positron emission tomography-computerised tomography (18FDG PET-CT) remains the gold standard.

Laparoscopic retroperitoneal para-aortic lymph node biopsy in advanced cervical cancer with pelvic lymph node metastases: A single-center prospective study

AIM

Extended-field concurrent chemoradiation therapy (Ex-CCRT) has been widely used for para-aortic lymph node (PAN) metastases confirmed by radiographic assessment without surgical exploration. The objective of this prospective study was to evaluate the clinical value of laparoscopic retroperitoneal PAN biopsy in locally advanced cervical cancer (LACC) with pelvic lymph node (PLN) metastases.

METHODS

From May 2017 to March 2020, stage IIB-IIIB cervical cancer patients who were diagnosed with PLN metastasis using positron emission tomography-computed tomography (PET-CT) with maximum standardized uptake value (SUVmax) ≥2.0 underwent laparoscopic retroperitoneal PAN biopsy. The radiation fields were extended to PAN areas with pathological metastases.

RESULTS

Fourteen patients were diagnosed with cervical squamous cell carcinoma of the International Federation of Gynecology and Obstetrics (FIGO) stage IIB (n = 7) and IIIB (n = 7). The median operating time was 138 min (range, 104-184 min). The median number of harvested PANs was 19 (range, 6-36). Three patients were positive for PAN metastasis on histological analysis. In this study, the sensitivity and specificity of PET-CT were 66.7% and 90.9%, respectively.

CONCLUSION

Our study is characterized by the use of more appropriate eligibility criteria for LACC with PLN metastases. Our results revealed that laparoscopic retroperitoneal PAN biopsy may be a useful approach to determine the radiation field for PANs during standard radiotherapy planning.

False negative rate at 18F-FDG PET/CT in para-aortic lymphnode involvement in patients with locally advanced cervical cancer: impact of PET technology

Background

The identification of factors responsible for false negative (FN) rate at ¹⁸F- Fluorodeoxyglucose (FDG) Positron Emission Tomography /Computed Tomography (PET/CT) in para-aortic (PA) lymph nodes in the presurgical staging of patients with locally advanced cervical cancer (LACC) is challenging. The aim of this study was to evaluate the impact of PET/CT technology.

Methods

A total of 240 consecutive patients with LACC (International Federation of Gynecology and Obstetrics, FIGO, stage IB2-IVA) and negative Magnetic Resonance Imaging (MRI) and/or Computed Tomography (CT) and negative ¹⁸F-FDG PET/CT in the PA region, undergoing laparoscopic PA lymphadenectomy before chemoradiotherapy were included. The FN rate in patients studied with Time of flight (TOF) PET/CT (TOF PET) or non-Time of flight PET/CT (no-TOF PET) technology was retrospectively compared.

Results

Patients presented with FIGO stage IB (n = 78), stage IIA-B (n = 134), stage III (n = 18) and stage IVa (n = 10), squamous cell carcinoma (n = 191) and adenocarcinoma (n = 49). 141/240 patients were evaluated with no-TOF PET/CT and 99/240 with TOF PET/CT. Twenty-two patients (9%) had PA nodal involvement at histological analysis and considered PET/CT FN findings. The FN rate was 8.5% for no-TOF PET and 10% for TOF PET subgroup respectively (p = 0.98). Ninety patients (38%) presented with pelvic node uptakes at PET/CT. The FN rate in the PA region was 18% (16/90) and 4% (6/150) in patients with and without pelvic node involvement at PET/CT respectively (19 vs 3% for no-TOF PET and 17 vs 5% for TOF PET subgroup).

Conclusions

In LACC, FN rate in PA lymph nodes detection is a clinical issue even for modern PET/CT, especially in patients with pelvic uptake. Surgical lymphadenectomy should be performed in case of negative PET/CT at PA level in these patients, while it could be discussed in the absence of pelvic uptake.

[Para-aortic lymph node staging in grade IB2 and above cervical cancers: Comparison of 18FDG PET-CT with para-aortic lymphadenectomy, using data from the Côte d'Or gynaecological cancer registry from 2003 to 2016]

INTRODUCTION

Current guidelines (ASCO, ESTRO, and ESGO) recommend para-aortic lymphadenectomy (PAL) for lymph node staging in patients with a negative initial PET-CT in locally advanced cervical cancer (LACC), with the aim to determine the radiation fields for radiochemotherapy. The main goal of this study was to compare overall survival (OS) in two groups, which differed according to the para-aortic lymph node staging technique used: imaging alone versus imaging and PAL. Secondary objectives were to determine recurrence-free survival (RFS), the proportion of false negatives on PET-CT, and surgery-related complications.

METHODS

We conducted a retrospective, observational study on data from the Côte d'Or gynaecological cancer registry collected from 2003 to 2016, and compared two groups of LACC with different techniques for staging para-aortic lymph nodes: PET-CT alone (iN group) (n=99) and PET-CT associated with PAL (pN group) (n=35) for a total of 134 patients.

RESULTS

OS (HR=1.04 (95% CI: 0.53-2.03); P=0.9) and RFS (HR=0.65 (95% CI: 0.29-1.45); P=0.29) were similar in both groups. There were 11.4% of false negatives in PET-CT, and 2.9% of patients who underwent PAL experienced complications. The staging method, iN or pN, had no impact on the time to the implementation of concomitant radiochemotherapy.

CONCLUSION

For lymph node staging in LACC, PAL after a PET-CT as compared with PET-CT staging alone, had no significant impact on OS or RFS.

Significance of para-aortic lymph node evaluation in patients with FIGO IIIC1 cervical cancer

OBJECTIVE

This study investigated the effect of para-aortic lymph node sampling or dissection in recently revised International Federation of Gynecology and Obstetrics IIIC1p cervical cancer treated with primary surgery and adjuvant radiation therapy with concurrent chemotherapy.

METHODS

We retrospectively reviewed the records of 343 patients with early-stage cervical cancer and pathologically proven pelvic lymph node metastasis following curative surgery from 2001 to 2014. No patient had imaging evidence of para-aortic lymph node involvement, and all patients received adjuvant concurrent chemotherapy with or without concurrent chemotherapy. We investigated the significance of para-aortic lymph node sampling or dissection on disease-free survival and overall survival.

RESULTS

After median follow-up of 58.3 months, 5-year disease-free survival and overall survival in all patients were 69.9 and 80.2%, respectively. Disease-free survival and overall survival did not differ between the para-aortic lymph node dissection group and the No para-aortic lymph node dissection group (P = 0.700 and P = 0.605). However, patients with para-aortic lymph node-positive disease had poorer disease-free survival and overall survival compared with those with para-aortic lymph node-negative disease (P < 0.001 and P < 0.001).

CONCLUSIONS

This study found no survival benefit of para-aortic lymph node evaluation among patients with International Federation of Gynecology and Obstetrics IIIC1p cervical cancer who were clinically para-aortic lymph node-negative. Although para-aortic lymph node metastasis is a poor prognosticator, the benefit of para-aortic lymph node dissection in terms of survival needs further investigation.

Prophylactic Extended-Field Irradiation in Patients With Cervical Cancer: A Literature Review

Currently, the standard radiation field for locally advanced cervical cancer patients without evidence of para-aortic lymph node (PALN) metastasis is the pelvis. Due to the low accuracy of imaging in the diagnosis of PALN metastasis and the high incidence of PALN failure after pelvic radiotherapy, prophylactic pelvic and para-aortic irradiation, also called extended-field irradiation (EFI), is performed for patients with cervical cancer. In the era of concurrent chemoradiotherapy, randomized controlled trials are limited, and whether patients with cervical cancer can benefit from prophylactic EFI is still controversial. With conformal or intensity-modulated radiation therapy, patients tolerate prophylactic EFI very well. The severe toxicities of prophylactic EFI are not significantly higher than those of pelvic radiotherapy. We recommend delivering prophylactic EFI to cervical cancer patients with common iliac lymph nodes metastasis. Clinical trials are needed to investigate whether patients with ≥3 positive pelvic lymph nodes and FIGO stage IIIB disease can benefit from prophylactic EFI. According to the distribution of PALNs, it is reasonable to use the renal vein as the upper border of the radiation therapy field for patients treated with prophylactic EFI. The clinical target volume expansion of the node from the vessel should be smaller in the right para-caval region than in the left lateral para-aortic region. The right para-caval region above L2 or L3 may be omitted from the PALN target volume to reduce the dose to the duodenum. More clinical trials on prophylactic EFI in cervical cancer are needed.

Tumour and pelvic lymph node metabolic activity on FDG-PET/CT to stratify patients for para-aortic surgical staging in locally advanced cervical cancer

PURPOSE

The aim of our study was to comprehensively evaluate the most valuable metabolic parameters of cervical tumours and pelvic lymph nodes (PLN) by FDG-PET/CT to predict para-aortic lymph node (PALN) metastasis and stratify patients for surgical staging.

METHODS

The study included patients with locally advanced cervical cancer, negative PALN uptake on preoperative FDG-PET/CT, and para-aortic lymphadenectomy. Two senior nuclear medicine physicians expert in gynaecologic oncology reviewed all PET/CT exams, and extracted tumour SUVmax, MTV, and TLG, as well as PLN. Prognostic parameters of PALN involvement were identified using ROC curves and logistic regression analysis.

RESULTS

One hundred and twenty-five consecutive locally advanced cervical cancer patients were included. The FDG-PET/CT false-negative rate was, respectively, 27.7% (13/47) and 5.1% (4/78) in patients with and without FDG-PET/CT PLN uptake. The AUC of cervical tumour size, SUVmax, MTV, and TLG was, respectively, 0.75 (0.62-0.87), 0.59 (0.44-0.76), 0.75 (0.60-0.90), and 0.71 (0.56-0.86). The AUC of PLN size, SUVmax, SUVmean, PLN SUVmax/Tumour SUVmax ratio, MTV, and TLG was, respectively, 0.57 (0.37-0.78), 0.82 (0.68-0.95), 0.77 (0.61-0.94), 0.85 (0.72-0.98), 0.69 (0.51-0.87), and 0.74 (0.57-0.91). The metabolic parameter showing the best trade-off between sensitivity and specificity to predict PALN involvement was the ratio between PLN and tumour SUVmax.

CONCLUSION

The risk of PALN metastasis in FDG-PET/CT negative PLN patients is very low, so para-aortic lymphadenectomy does not seem justified. In patients with preoperative PLN uptake on FDG-PET/CT, surgical staging led to treatment modification in more than 25% of cases and should therefore be performed. Patients with more than one positive PLN and high PLN metabolic activity are at high risk of para-aortic extension and recurrence. Further prospective evaluation is required to consider intensified treatment modalities without prior PALN dissection.